1. Field of the Invention
The present invention relates to an image recording apparatus which is capable of recording an image on a sheet transported along a transport passage.
2. Description of the Related Art
An image recording apparatus, which is capable of recording an image on a sheet, is provided with a transport passage for the sheet therein in most cases. In the image recording apparatus, the sheet is interposed by roller pairs, and thus the sheet is transported along the transport passage. For example, an ink-jet printer is known as an image recording apparatus which is provided with a recording section for recording an image by discharging inks from an upward position to the sheet, and a platen provided under or below the recording section with a transport passage intervening therebetween for supporting the sheet.
In order to avoid the floating of the sheet during the image recording, Japanese Patent Application Laid-open No. 2000-71532 discloses an ink-jet recording apparatus in which the sheet is curved in a wavy form (wavy shape) in the direction (hereinafter simply referred to as “widthwise direction”) perpendicular to the transport direction so that the strength is strengthened with respect to the bending of the sheet in the transport direction.
In the case of the ink-jet recording apparatus disclosed in Japanese Patent Application Laid-open No. 2000-71532, the sheet is curved by being interposed between a platen 11 which has ribs 13 and recesses 15 and a sheet holding plate 12 which has projections 16. The projections 16 are arranged while being aligned in the widthwise direction. Therefore, the sheet is curved approximately simultaneously at all portions in the widthwise direction at the timing at which the downstream end in the transport direction arrives at the sheet holding plate 12. In this situation, in order to curve the portions disposed in the vicinity of the center of the sheet in the widthwise direction, it is necessary that the both end sides of the sheet should be pulled up to the center respectively. However, a large force is required to pull the sheet portions up to the center in the state in which the both end sides of the sheet are pressed by the projections 16. Therefore, the portions, which are disposed in the vicinity of the center of the sheet in the widthwise direction, are hardly curved as compared with the portions disposed on the both end sides, wherein the amplitude of the formed wave is small. As described above, in the case of the conventional structure or arrangement, a problem arises, for example, such that the amplitude of the wave formed by the sheet is dispersed in the widthwise direction. Usually, it is possible to raise the accuracy of the image recording when the amplitude of the wave formed by the sheet is less dispersed.